Electrographic recorder wherein image is instantaneously rendered visible

ABSTRACT

In an electrographic recording apparatus, a stylus support member having a leading extremity and trailing extremity in the direction of recording scan separated by a distance sufficient to prevent the fibers of a developing applicator from being pinched by the recording stylus at their point of contact with the recording medium.

United States Patent Inventor Howard D. Ring Rochester, N.Y.

Appl. No. 14,096

Filed Feb. 25, 1970 Patented Oct. 5, 1971 Assignee Xerox Corporation Rochester, N.Y.

ELECTROGRAPHIC RECORDER WHEREIN IMAGE 1S INSTANTANEOUSLY RENDERED VISIBLE 5 Claims, 3 Drawing Figs.

U.S. Cl 346/74 ES, V l 17/ l 7.5 Int. Cl ..G0ld15/06,

G03g 13/06, G03g l5/08 [50] Field of Search 346/74 ES. 74 MP; ll7/l7.5; 96/13 [56] References Cited UNITED STATES PATENTS 3,308,473 3/1967 Sawazaki 346/74 ES Primary Examiner-Bernard Konick Assistant Examiner-Gary M. Hoffman Attorneys-James J. Ralabate, John E. Beck and Benjamin B.

Sklar ABSTRACT: In an electrographic recording apparatus, a stylus support member having a leading extremity and trailing extremity in the direction of recording scan separated by a distance sufficient to prevent the fibers of a developing applicator from being pinched by the recording stylus at their point of contact with the recording medium.

PATENTEUUBT SIB?! 3.611.018

INVENTOR. HOWARD D. R l N G A TTORNE V ELECTROGRAPHIC RECORDER IMAGE IS INSTAN'IANEOUSLY RENDERED VISIBLE This invention relates generally to electrographic recording and, specifically, to electrographic recording styli supports.

Electrography may be generally defined as the recording process wherein electrostatic chargesv are deposited onto an insulative recording medium by the action of a conductive stylus or writing electrode which is suitable pulsed with voltage of a predetermined amplitude.

The recording medium is generally a plastic coated paper stock or may be simply a sheet of plastic. The insulative properties of this medium serve to maintain the electrostatic charge deposited thereon so that there is no lateral or other leakage or dissipation of this charge.

In most applications where electrographic recording is put to a practical use, relative motion between the conductive stylus and the recording medium is maintained and recording pulses are supplied to the stylus as functions of information to be recorded.

Since the electrostatic charges deposited onto the recording medium are not readily visible, development of these recordings is necessary before the recorded information can be useful. A preferred method of developing the latent electrostatic charges has been to contact the charges with electroscopic marking particles, commonly referred to as toner, which electrostatically adhere to the latent recordings to render them visible. These particles may be brought into developing contact with the recording medium through the use of an applicator having a fibrous developing surface constituted by something such as natural or synthetic fur.

The developed information may thenbe made permanent by conventional fusing techniques whereby the usually thermoplastic marking particles are heated to fuse with the surface of the recording medium.

In certain applications it is very desirable to develop the deposited charges as rapidly as possible so that the recorded information may be seen immediately. Such an application may be in an electrographic typewriter.

Altemately, certain recording media may, because of their inability to hold the recorded charges for any appreciable length of time, necessitate almost instantaneous development.

However, due to the preference that the recording stylus contact the surface of recording medium during recording, it has been discovered that inconsistent recording has resulted when fibrous applicators have been used in the development step. Because of the need for rapid development, the fibers of the developing applicator have been made to actually envelop the stylus as it has moved from one margin of the recording medium to the other. By this it is meant that at various times during a recording scan or cycle, the stylus has been driven through the fibers of the developing applicator as development was taking place. In this manner, the fibers at the trailing edge of the stylus serve to develop the recorded charges while the fibers at the leading edge of the stylus are struck sharply as the stylus continues the recording scan or pass.

Slow motion photography has revealed that as the leading edge of the stylus moves through the fibers of the applicator, individual fibers are deflected in such a way that their free ends are pinched between the stylus and the recording medium at the point on contact therebetween. Although the diameter of the fibers is not great, these few fibers so caught by the stylus are sufficient to upset the carefully determined recording parameters to result in poor or inconsistent recording. In addition, in some instances the fibers themselves are broken or pulled from their support.

Therefore. it is an object of the present invention to improve electrogruphic recording where fibrous developing applicutors are employed to envelop the stylus during recording.

Another object of the present invention is to provide an improved electrographic recording stylus which can record consistently in the presence of a developing fibrous applicator.

A still further object of the present invention is to provide an improved electrographic recording stylus which does not damage a fibrous applicator used to instantaneously develop the recorded electrostatic charges.

These and other objects may be accomplished in accordance with the principles of the present invention wherein the support member for the recording stylus is designed so that the leading edge of the support is separated from the trailing edge or contact point with the recording medium by distance greater than the average length of fiber of the developing applicator less an amount equal to the distance separating the leading edge of the stylus support and the fixed end of the fibers of the applicator:"

Other objects and features of the present invention will become more apparent when the following detailed description of the present invention is read in connection with the appended drawings wherein: g

FIG. 1 illustrates a partial view of an electrographic recording apparatus having a recording stylus enveloped by a fibrous applicator during the recording cycle:

FIG. 2 is a front view of the stylus support in accordance with the present invention: and

FIG. 3 illustrates an alternative stylus support in accordance with present invention.

Referring specifically to FIG. I there is illustrated electrographic recording apparatus with certain portions not shown. A web or recording medium 2 is shown and usually is positioned at a recording zone by a backing electrode or platen not shown in FIG. I. The illustrated arrow 4 depicts the direction of travel of the recording medium during the recording process.

As mentioned hereinabove, the recording process itself is accomplished through the use of a conductive stylus shown generally by reference numeral 6 which may include a plurality of conductors or pin electrodes which at one point contact in a linear arraythe recording medium 2 in the recording zone. As will be noted in greater detail in the description'of FIG. 2 the other terminals of these pin electrodes or conductors may be positioned approximate to a portion of the stylus support 8 to form spade electrodes which may be plugged into a suitable socket in the movable carriage for the stylus.

It is sufficient with respect to FIG. I to refer to the stylus support 8 as being generally as insulative material having sufficient resiliency to maintain the conductors 6 in recording contact with the medium 2. The arrow shown between the stylus support and the recording medium depicts the direction of travel of the stylus and its support during the recording process. I 1

FIG. 1 illustrates the manner in which, for instantaneous development, the stylus support 8 is enveloped by the fibers 10 of the fibrous applicator generally referred to by reference numeral 12.

As shown, the applicator may have a support shaft 14 to which rotative power may be supplied to move the applicator through its development cycle. In addition to this, an outer core or support member 16 fixed to rotate with shaft 14 forms the actual support structure for the fixed ends of the fibers 10.

As FIG. I is viewed, it can be appreciated from the drawings that the right extremity of the stylus support'member 8 is the leading edge while the portion of the stylus support approximate to the point of contact with the recording medium and the conductors constitutes the trailing edge.

In practice, therefore, as the stylus 6 mounted on the stylus support 8 is moved from left to right across the recording medium 2 portions of the fibers 10 are swept close to the trailing edge ofthe stylus support 8 and in contact with the recording medium just as the stylus 6 deposits electrostatic charge thereon. This permits instantaneous development of these charges as the stylus continues in its traversal to the right margin of the recording medium 2. Accordingly. at the leading edge of the stylus support a deflection of the fibers is depicted in FIG. 1 to illustrate the force which the leading edge of the stylus support exerts on the fibers themselves. Between the leading and trailing edges of the stylus support member 8 the fibers are simply deflected almost to a vertical position as the shaft 14 moves the applicator 12 about its axis.

From FIG. 1 it can be observed that the distance between the leading and trailing edges of the stylus support 8 is such in comparison to the average length of the fibers 10 so that those fibers struck by the leading edge are not deflected into a pinched relationship between the trailing edge of the stylus support member 8 and the recording medium 2. In this manner as the stylus support member 8 is driven through the fibers of the applicator 12 they are unable to be pinched between the trailing edge and the recording medium even though the moving leading edge deflects them into the area between the stylus support member and a recording medium.

Referring now to FIG. 2, there is shown a view of the stylus support member 8 and the stylus carriage 18 shown partially with the terminal socket 20 mounted thereon to receive the stylus support member 8. FIG. 2 depicts a view of the stylus support member referred to hereinabove in connection with FIG. 1 as seen from approximately where the shaft 14 is located. Aswas noted above, the stylus support member has a leading edge generally designated by reference numeral 22 and a trailing edge designated by reference numeral 24.

It may be appreciated from the view of the stylus support member 8 as shown in FIG. 2 that the stylus or pin electrodes or conductors are on the side not displayed by FIG. 2. As is well known in the art, printed circuit techniques may be employed to apply or deposit these very thin conductors to the surface of the stylus support member 8. The electrical signals may be supplied to these conductors via the socket structure 20 into which the stylus support member 8 plugs.

As will be appreciated, the stylus carriage 18 may be supported on a pair of parallel rails or other guide structures so that it may be moved back and forth driving the pin electrodes through the recording zone.

FIG. 3 shown an alternative embodiment to the stylus support structure illustrated in FIGS. 1 and 2. The difference being the portion designated by reference numeral 26 which may be referred to as a protrusion or shield portion which forms the leading edge of the stylus support member 8.

Depending upon the average length of the applicators fiber it can be appreciated from FIG. 3 and the principles of the present invention that the portion of the stylus support member being enveloped by the fibers of the developing applicator may be artificially extended as is shown in FIG. 3.

In certain instances this may be most desirable when the distance between the core or support member 16 of the applicator I2 is separated from the recording medium in the recording zone by distance less than the average length of the fibers 10. In certain instances this may have some developing characteristic which is desirable and consequently the distance between the leading and trailing edges of the stylus support member 8 must be such as to insure isolation between the fibers at the leading edge of the moving support member 8 and the trailing edge in contact with the recording medium 2. Since development of the latent electrostatic charge deposited by the conductive styli is possible only after the trailing edge passes over the recording medium, the shield or protrusion 26 in the embodiment of FIG. 3 may be extended in the direction of recording as far as needed considering, of course, the momentum of the stylus assembly itself at the recording speeds involved as well as the average length of the fibers 10 used in the developing applicator.

As shown, the protrusion 26 has a rounded configuration to facilitate passage through the fibers to minimize interference. Other configurations may be possible and the present invention is not intended to be limited to those configurations shown in FIGS. 2 and 3.

In summary, a stylus support member has been described used in electrographic recording apparatus where the stylus is physically enveloped by the fibers of a fibrous developing applicator and wherein the portion of the stylus support member so enveloped has two extremities forming a leading edge in the direction of movement during recording and a trailing edge which is proximate to the contact point between the conductors so supported and the recording medium so as to prevent fibers from being pinched between the conductors and the recording medium at the point of contact therebetween.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention.

In the claims:

1. In an electrographic recording apparatus wherein the electrostatic patterns deposited on the recording medium are instantaneously rendered visible by transfer of electroscopic marking particles from a developing applicator having fibers, a recording assembly comprising:

a. a support member having a leading edge and a trailing edge relative to the direction of movement of said member during a recording cycle;

b. at least one recording stylus supported by said support member for recording contact with said recording medium at said trailing edge;

c. said edges being separated by a distance greater than the average length of said fibers.

2. An electrographic recording apparatus comprising:

a. means for positioning a insulative recording medium in a recording zone;

b. at least one conductive stylus having one end in contact with said recording medium and adapted to be pulsed with recording signals for placing electrostatic charge patterns on said medium;

c. a developing applicator means having fibers of an average length for conveying marking particles to said recording zone to render said charge patterns visible, said applicator means positioned so that said fibers pass through said recording zone during a development cycle;

d. support means for supporting said conductive stylus in said contact and adapted for movement through said recording zone in a predetermined direction during a recording cycle and into interference with said fibers, said support means having two extremities in said predetermined direction, said extremities being separated by a distance greater than said average length of said fibers.

3. A support member for a conductive stylus which is moved in a predetermined direction during a recording scan across and in contact with a recording medium in a recording zone to deposit latent charges thereon to be developed by particles from a fiber bearing developing applicator,

said support member having a portion opposite said recording zone which interferes with said fibers during said recording scan, said portion having leading and trailing edges separated by a distance sufficient to prevent those fibers of said applicator deflected by said leading edge from being pinched between said recording stylus and said recording medium.

4. In an electrographic recording apparatus wherein a conductive stylus is enveloped by the fibers of a developing applicator as the stylus is moved in a direction across and in con tact with a recording medium for depositing electrostatic charges thereon, a stylus support member comprising:

a. a first elongated member extending transverse to said direction,

a second elongated member rigidly fixed to said first elongated member and extending substantially parallel to said direction, said second elongated member having a leading and trailing edge in said direction, the latter edge being proximate to the point of contact between said stylus and said recording medium, the distance between said leading and trailing edge being sufficient to prevent fibers of said applicator from interfering with said contact during the envelopment of said stylus thereby.

5. A stylus support member as defined in claim 4 wherein said leading edge is spacially advanced in said direction from said first elongated member. 

1. In an electrographic recording apparatus wherein the electrostatic patterns deposited on the recording medium are instantaneously rendered visible by transfer of electroscopic marking particles from a developing applicator having fibers, a recording assembly comprising: a. a support member having a leading edge and a trailing edge relative to the direction of movement of said member during a recording cycle; b. at least one recording stylus supported by said support member for recording contact with said recording medium at said trailing edge; c. said edges being separated by a distance greater than the average length of said fibers.
 2. An electrographic recording apparatus comprising: a. means for positioning a insulative recording medium in a recording zone; b. at least one conductive stylus having one end in contact with said recording medium and adapted to be pulsed with recording signals for placing electrostatic charge patterns on said medium; c. a developing applicator means having fibers of an average length for conveying marking particles to said recording zone to render said charge patterns visible, said applicator means positioned so that said fibers pass through said recording zone during a development cycle; d. support means for supporting said conductive stylus in said contact and adapted for movement through said recording zone in a predetermined direction during a recording cycle and into interference with said fibers, said support means having two extremities in said predetermined direction, said extremities being separated by a distance greater than said average length of said fibers.
 3. A support member for a conductive stylus which is moved in a predetermined direction during a recording scan across and in contact with a recording medium in a recording zone to deposit latent charges thereon to be developed by particles from a fiber bearing developing applicator, said support member having a portion opposite said recording zone which interferes with said fibers during said recording scan, said portion having leading and trailing edges separated by a distancE sufficient to prevent those fibers of said applicator deflected by said leading edge from being pinched between said recording stylus and said recording medium.
 4. In an electrographic recording apparatus wherein a conductive stylus is enveloped by the fibers of a developing applicator as the stylus is moved in a direction across and in contact with a recording medium for depositing electrostatic charges thereon, a stylus support member comprising: a. a first elongated member extending transverse to said direction, a second elongated member rigidly fixed to said first elongated member and extending substantially parallel to said direction, said second elongated member having a leading and trailing edge in said direction, the latter edge being proximate to the point of contact between said stylus and said recording medium, the distance between said leading and trailing edge being sufficient to prevent fibers of said applicator from interfering with said contact during the envelopment of said stylus thereby.
 5. A stylus support member as defined in claim 4 wherein said leading edge is spacially advanced in said direction from said first elongated member. 